1. Field of the Invention
The present invention relates to a metal oxide/silica composite and a cosmetic preparation comprising thereof, particularly to an improvement of dispersibility of the metal oxide.
2. Background Arts
When compared with ultra-violet (UV) ray absorbing agents represented by octylmethoxycinnamate, UV protective powders such as titanium oxide or zinc oxide are advantageous in their safety while they are disadvantageous in their giving a whitish shade when applied on the skin, which may cause an artificial finish. To meet this problem, when particles of titanium oxide are coated with a transparent powder such as silica or the like, it is known the transparency of those particles is improved. It is also known that, when ultra-fine particles of titanium oxide or zinc oxide or a sol solution of such a compound is added to a cosmetic preparation, the transparency of the preparation is more emphasized as compared with the same preparation to which a conventional powder of zinc oxide or titanium oxide has been added.
However, when particles of titanium oxide are coated with a transparent powder of silica or the like, the resulting powder tends to lose its UV protection activity in proportion with the increased fraction of the coat. It has been established that, when ultra-fine particles of titanium oxide or of zinc oxide, or a sol solution of such a compound is added to a cosmetic preparation, the particles or the sol settles on the bottom over time, to aggregate there, which may act as a factor responsible for reducing the UV protection activity of the preparation, or for interfering with its stability.